Tubular heat exchangers



Sept- 11, 1956 P. s. MONROE ET AL 2,762,611

TUBULAR HEAT EXCHANGERS Filed Feb. 2s, 1952. s sheets-sheet 1 P. S.MONROE ET AL TUBULAR HEAT EXCHANGERS Sept. l1, 1956 Filed Feb. 28. 1952'5 Sheets-Sheet 2 BY Enh/W77;

S WL N N m. r gm l N A m a 6 o Sept. 11, 1956 P. s. MONROE :rAL2,762,611

TUBULAR HEAT EXCHANGERS IN VEN TORS PA UL s. HvA/Ros,

DONA L D KEA PPe? A770?? EYS -iron or steel tube in a sterilizer unit.

2 ,762 ,6 l Patented. Sept. 1 1 ,11956 TUBULAR HEAT XCHANGRS "Paul S.Monroe, Chatham, N. J.,'and"Donald Krapp, Ver- Imilion, and Stanley C.Orr, Elyria, Ohio; said Donald Krapp, now by change of name 'DonaldKropp, as- "signors'to The Pfaudler Co., Rochester, N. Y., acorlporation of New York Application February 28, 19:52, 'Serial No.273;924

'1 Claim. (Cl. 257-240) The present invention relates vgenerally to theheat exchanger art and is more particularly concerned With a noveltubular heat exchanger comprising a novel Vcombination of elements whichalords unique advantages and unique combinations of advantages ofsubstantial'imporf tance.

Although tubularl heat Vexchangersin general have been known and widelyused for many years, there has long existed an unsatisfied demand fortubular heat exchangers which could be used for handling fluidscorrosiveto the exchangers under operating circumstances. This corrosionproblem has persisted down to the timeof the 'present invention, despitethe kfact that `the needv for a tubular heat exchanger which Vwould'fully solve r`the .problem has never diminished. HoWever,this-demand:has'brought forth many etorts by those skilled in the art andhasresulted in a number 'and variety of publications which fail to disclosea solution to ythis problem but serve "to illustrate thel needfor thepresent invention.

' One'of the priorefforts'at solving-this problem-'involved thevsubstitutionot' a'fused'quartz tube forrau This-fconstruction, however,neverbecame practical 'or VcommercialV and\to the best ofour'lcnowledge, no hear-exchanger has Lever been vmade heretofore inaccordance-With this proposal.

The expense and d'itliculty'of constructing adevice' offthis"kindl'wouldbe excessiveand itsservice life"'would be *brief duel to thediicu'lty of effectively a'ndlastingly seal- -i-ng the quartzdtube in*lthe 'asSernbly-and also due t-o the forces imposed-upon these' tubesIdue tothermalfcoeicient ditterentialsbe'tween the quartzandlthefmetalelements `engaged andsealed together in the-assembly.

l' In 'accordance with the present invention, the :ditiiculties andshortcomings of the quartzftube heat exchanger con- 'structionv andtheother prior art shortcomings-sand ydere- 4li'ctions have beenovercome and eliminated. Thus, by

virtue ofthisinvention, a tubular heat exchanger in which one or aplurality of tubes are provided'in a heat `exchanger-shell canbemadewithelements Which'cannot be used in accordance with thepriorartandwhich en- -able use of the Yheat exchanger for protracted periodsunyder conditions Whichfwould rapidly destroy the hereto- 4foreconventional devices. Still further, the devices of this invention maybey easily constructed andv assembled l and also may be readilydisassembled for maintenance or repair. As another advantage of thedevices ofthe pres- -ent invention, they open an entirely new and Widerange of materials which may be used for best results for variousspecific purposes. Moreover, this result is 'obtained without in anywaydiminishing or sacrificing-sealing effectiveness or necessitatingchanges in any respect inthe basic lspecifications of heat exchangers asto dimensions, ma-

terials of construction or the routine of the 'assembling andinstallationl operations.

As 'another advantage of this invention, in a preferred embodiment'wherethere is the slightest leakage'thro'ugh a tube sheet'at one end or theother of a heat exchanger the'failure ofl the sealing means can beimmediatelydetected Withoutthe necessity-of disassembling-.the exchangerto any extentwhatever. Y

Interchangeability oftubes. as to various outside ,diameters and as^tothe materialspftube construction is still another unique and importantadvantage'of -this invention.

Those skilled in the art will gain a further and. better understandingof this invention upon consideration of the detailed description ofseveral exchangers of thisinvention, reference being had to? thedrawings accompanyin'gand formingfa part of this specication; in which:

`* Fig. l is a fragment-ary, longitudinal sectional view of a heatexchanger embodying this inventionl'in a preferred form;

Fig. 2 is a'fragrnentary, longitudinal'sectional Viewl of the' device ofFig. l with the tube assemblyanditbe sheets removed to show the b'afe'assembly' Within the exchanger shell;

Fig. 3is' a transverseseeti'onalview taken on 'line`3-'3 Fig. 4isaifragmentary,lorigitudinal Vsectional'vieiv `of -a vjpacketed heat'exchangershell of this) invention;

V:Fig 5 is a'transversesectionaliviewtaken'onlineSS :Fig: 6 is' a*fragmentarylview fof' another' preferred' type Vofheatexchangerofthisnvenftion, shovvin'g'anen'd porl'tion thereof infdetail;

ghtly the yshell between I`-the-tubes-'and the .tubesheets -'Thissecuring vand sealingmeans generally-includesdeformable 'annuli whichsurround andv fsealin'glyf bearsagainSt-annular portions of .each 'tube.endpportioni and fagainst annular portions ofl eachtu-besheet-"adjacent: to lsaidf-tubenend portions.

The.v shell ofthis 1 device lis :suitably generallyfcylindrical yandhasend-'.portions'whichfare open. fGeneralIyuc'ayIindrical anged'bonnetsare clamped orotherwisefzsecured lto each "end'ofthe'fshellftolserve asheaderimeansfor delivering fluid into the tubes ofthe as'semblyandrWi'th- "drawing it therefrom. r`Any vsuitable-clarnp`meansilrnay vbe used for: securing the1bonnets 'tot thefshell-y andthe'fshell may be constructed of virtually any desired-material having--the strength qualities and' corrosion-resistance required for theintended use. Insome'instances''aglass-linedE i'ron lor steel shell maybe 'employed-where,-for.instanceyacid resistance is va primaryconsideration.

In reference particularly to the heat exchangerillustrated in-Figs. l, 2and -3, thisapparatus comprises an elongated, generally cylindricalshell 1'0 vvhich-isopen -at each end and which is providedwith huidinlet and tended for use, for example, in a chemical plant in thehandling of acids which are corrosive to ferrous metals, such ashydrochloric acid and sulphuric acid.

This heat exchanger comprises seven tubes 19 arranged in threeparallel-tiers, as indicated in Fig. 3, these tubes being longer thanshell including end flanges 14 to extend through the shell and projectfrom the ends thereof and thus facilitate assembly with the tube sheetsand the bonnets of the assembly subsequently to be described. Tubes 19,like shell 10, are suitably of steel which is protected from contactwith corrosive iluids within the shell by means of glass coatingscovering the outer surfaces of the tubes.

For the purpose of directing and controlling the flow of heat exchangefluid from shell 10 from inlet port 11 to outlet port 12, a bailleassembly B is provided within the shell as illustrated in Fig. 2.Battles 20 of assembly B are of thin section and generally semi-circularand they are arranged to provide a tortuous passage for fluid betweenthe said ports, adjacent baffles being spaced apart but in effectpartially overlapped. Baffles 20 are secured in place against gravityand pressure exerted by heat exchange fluid ilowing through the shell incontact with the tubes by means of tie rods 22. Each of these rodsserves to join three baffles together. Bafiles 20 are provided withtransverse apertures through which tubes 19 extend. The tie rods areassembled and held in place with nuts 23 screwed on threaded ends of therods to atord adjustability and provide a rigid structure providing thedesired flow characteristics in heat exchange fluid. The end rod 22 ofbale assembly B extends through the end of shell 10 for engagement witha tube sheet thereby to stabilize the assembly and prevent it fromshifting lengthwise of the shell in use. Baiiles 20, tie rods 22 andnuts 23 are all suitably of material which will be resistant to the uidto be run through shell 10 in contact with the outer surfaces of tubes19. We have found, however, that when these items are made of Karbatewhich is a compressed, bonded rigid graphite-amorphous carbon mixturemanufactured and sold by the National Carbon Co., or Haveg which is acompressed and bonded mixture of phenolformaldehyde-type resin andasbestos manufactured and sold by Haveg Corporation, they are generallysatisfactory for a wide variety of purposes, being resistant to mostorganic and inorganic acids to which glass is resistant.

A pair of tube sheets 25 are provided to close the ends of shell 10 andwhile they are of steel, these elements are glass-covered, as indicatedat 26, for acid resistance.

These tube sheets have transverse openings 28 through which the ends oftubes 19 may extend, as shown in Fig. l without engaging said tubesheets. The radius of sheets 25 is substantially the same as the radiusof end anges 14 to facilitate the liquid-tight attachment of the tubesheets to the shell.

Packing material of any suitable type resistant to the acid or othercorrosive substances to be contained in the shell is provided in theform of a pair of thin, ilat rings 29 of a radius correspondingsubstantially to flanges 14. Tube sheets 25 are assembled with theserings 29 disposed between them and the end anges of the shell to preventleakage of lluid from the shell between said sheets and anges.

The means for sealing the tubes in assembly with the tube sheetscomprises in this Fig. 1 heat exchanger an annular body 31 of packingmaterial of the required anticorrosion characteristics. Annulus 31 ineach instance is of internal diameter conforming substantially to theexternal diameter of tubes 19 so that when these rings are slipped onthe tubes they sealingly grip said tubes. In transverse section rings 31are of trapezoidal shape to assure their iirm sealing engagement withnot only the tube in each instance, but with tube Asheet 26, the base ofof the trapezoidal section bearing against an annular portion of thetube whilethe sloping sides thereof bear against the tube sheet andagainst retaining means including a portion of a bonnet member 35.

Bonnet 35 is of generally cylindrical shape and has a tube sheet 36opposed to a tube sheet 25, an outer wall 37 spaced therefrom andprovided with a port 38 for delivery to or discharge of iluid from apipe header chamber 39 within the bonnet. Tube sheet 36 has seventransverse openings for registry with openings 28 in the tube sheets toreceive the end portions of tubes 19 and these inner wall openings arethreaded for a purpose to be described. This bonnet inner wall inaddition is of substantially the same diameter as the tube sheets and inthe illustrated assembly this portion of the bonnet is disposed closelyadjacent to the outer side of a tube sheet, being spaced therefrom bymeans of a ring 40 of packing material of substantially the samediameter as packing ring 29. Ring 40, however, is provided with a slot41 in its lower portion to allow for drainage from the heat exchanger ofany iluid leaking through the tube sheets or inner wall 36.

Rings 31 are retained in position, as indicated above, by hollow nuts 44screwed in the openings in tube sheets 36 of the bonnets, these nutshaving inside diameters at their inner ends greater than the outsidediameter of the tube ends. Thus, `tubes 19 are received in the innerends of nuts 44 without engaging the nuts but the nuts are rmly engagedwith the trapezoidal packing rings 31 and are in addition, readilyremovable and are adjustable to make allowances for variations inpacking ring shape and dimensions.

In the apparatus of Fig. l, each of the bonnets is provided with abulkhead 46 extending axially of the bonnet and thereby dividingchambers 39 into two parts. The purpose of this is to provide for flowof uid through the tubes in certain predetermined sequence as indicatedin the drawings.

The Fig. 1 assembly is held together by means of eight adjustable clamps50, metal rings 51 being welded to the outer peripheral portions of endflanges 14 and to the bonnet tube sheets 36 to provide means foranchoring these clamps in position to hold the assembly together.

Shell 53 illustrated in Fig. 4 is basically similar to shell 10, but isjacketed over most of its length between the inlet and outlet ports 54and 55. The provision of jacket I is desirable in the case whereadditional condensing surface is required for increased efficiency ofthe heat exchange operation or for increased capacity of the heatexchanger. Jacket J comprises a cylindrical portion 57 of internaldiameter substantially greater than the outside diameter of shell 53whereby a chamber 58 is dened between these two elements for the ow ofheat exchange iiuid in contact with the shell outer surface. The ends ofcylinder 57 are closed, rings 59 being welded to shell 53 and to thiscylinder, and inlet and outlet pipes 60 and 61 are formed on cylinder 57for delivery of heat exchange iluid into and removal of such iluid fromthe chamber 58 through openings provided for this purpose in the saidcylinder near its ends.

Referring to Fig. 6, the heat exchanger shown comprises a shell 10described above and a tube sheet 65 having transverse apertures 66 ofreduced diameter at their inner ends and increased diameter in theirmid-sections and at their outer ends. Thus tubes 19 cooperate withsheets 65 to deiine passages through these sheets which are constrictedadjacent to the inner sides of the sheets -but are enlarged toward theouter sides thereof, the tubes, however, being spaced from the sheets atall points. The purpose of this unique tube sheet structure and tubesheet-tube relationship is to provide for maximum sealing eifect inhigh-pressure and long-service operation. Packing P thus is disposed inthese passages to bear against an annular shoulder 69 defined in tubesheet opening and engages opposed annular portions of the tube sheetsand the end portion of the tubes extending therethrough. Preferably, asshown a plurality of deformable packing ring elements 70 are located inthese passages in huid-sealing engagement with the tubes and the tubesheets and are retained in this position by means of retaining nuts 44screwed into inner wall 71 of a bonnet 72.

Bonnets 72 are basically similar to bonnets 35 but have fluid inlet ordischarge ports 73 in their side walls instead ot their end walls andtherefore pipe connections 74 extending radially instead of generallyaxially of shell 10. The tube sheets 65 are spaced from and sealinglyrelated to flanges 14 and inner wall 71 by means of gasket rings 67,which unlike gaskets 40 are not slotted.

The Fig. 7 assembly differs from those described above in that anged endportion 77 of its shell 76 extends across the end of the shell and isprovided with a plurality of transverse openings 79 through which tubes$0 of the assembly extend without engaging the said flange portion. Alsoin this Fig. 7 apparatus, neither the shell, the iiange portion 77, nortubes 80 are provided with a glass protecting coat or other specialcorrosion-resistant covering, but the tubes and tube sheet 82 andcommunicating vessel 90 are composed of corrosion-resistant metal. Thus,in this Fig. 7 assembly the shell 76 is not exposed to the corrosionfluids owing in contact with the tubes, or in other words, it is thetube-side rather than the shellside which must be corrosion-resistant,unlike the assemblies of Fig. l or 6. Tube sheet 82 has transverseopenings 83 in register with openings 79, the diameter of these openings83 being greater than the outside diameter of the tubes to provide forclearance between the tubes and these elements in accordance with thisinvention. The tubes are sealed in position and assembly with the tubesheet and the shell by means of deformable annuli S5 which bear againstannular portions of the ends of the tubes and against the outer surfaceof the shell frange discs and against the inside surface of the tubesheets. it may be noted that unlike the arrangement in Fig. 1, inaccordance with the Fig. 7 construction, sealing rings 85 -are disposedto the inside of the tube sheet rather than to the outside thereof.However, as in the Fig. l assembly and more noticeably in the Fig. 6assembly, these rings are disposed between opposed annular portions orthe tube sheets and the tube end portions. The tube sheets in the Fig. 7embodiment thus function as means for securing and supporting the tubesin place and for sealing the tubes and tube sheets together by virtue ofthe fact that in cooperation with shell flange discs 77 the tube sheetshold the sealing annuli firmly in location against the tubes.

In this Fig. 7 assembly, the bonnet is a fabricated cylindrical body 90which is open at one end and is provided with a ange 91 and at its otherend has a pipe connection 94 for delivery of uid into or receipt of tuidfrom the tubes of the apparatus.

Tube sheets 82 and the bonnets 90 are held together with shell 76 bymeans of a plurality of nuts 96 and bolts 97 the bolts extending throughregistered openings in the peripheral portions of flange 91, the shellilange and the bonnets and through an outer portion of the tube sheet,nuts 96 being screwed on the threaded ends of bolts 97 to establish andmaintain the desired pressure on a flat ring 99 or packing materialdisposed between the outer sides of the tube sheets and the opposedinside portion of bonnet flange 91.

Instead of using glass-lined tubes in the heat exchangers of thisinvention, tubes of glass, noble metal-clad tubes, tubes of porcelain,Duriron, Hastelloy and similar metals, alloys and ceramic materials, maybe ernployed to realize the advantages of this invention set forthabove.

Similarly, as indicated above in reference to Fig. 7, the bonnets, tubesheets and other parts such as packing retaining nuts may be of glass ormay be glass-lined, noble metal-clad or other special type in order torealize the advantages of this invention set out above.

Having thus described the present invention so that others skilled inthe art may be able to gain a better understanding and practice thesame, we state that what we desire to secure by Letters Patent isdefined in what is claimed.

What is claimed is:

A heat exchanger tube and tube sheet assembly comprising a tube sheethaving a transverse aperture of enlarged diameter at one end and reduceddiameter at the other end and an annular abutment between the ends ofthe aperture, a tube extending through said aperture in spaced relationto the tube sheet and cooperating with the tube sheet to define anannular chamber, packing in said chamber comprising a deformable annulussurrounding a portion of the tube in said tube sheet and bearing againstopposed portions of the tube and tube sheet, a support wall spaced fromthe tube sheet and opposing the outer side thereof, and a packing glandthreadably engaged with said support wall and having an annular endportion projecting into said chamber and pressing the packing intosealing engagement with the tube sheet and tube within said chamber,said annular end portion of the packing gland having an inside diameterapproximating the minimum diameter of the tube sheet aperture and beingin axial and radial spaced relation to the end of the tube extendingthrough the tube sheet whereby the tube is held in fioating spaced andsealed relation to the tube sheet for limited relative axial and radialmovement.

References Cited in the tile of this patent UNITED STATES PATENTS1,183,312 Martin May 16, 1916 1,892,377 Bergskaug Dec. 27, 19321,948,550 Voorheis Feb. 27, 1934 2,394,402 Pennella Feb. 5, 1946 FOREIGNPATENTS 273,605 Great Britain Nov. 12, 1926 549,431 Great Britain Nov.20, 1942

